This invention relates generally to the mounting of acoustic diaphragms in loudspeakers, microphones or the like, and more particularly to an annular suspension for supporting the outer and/or inner edge portion of an acoustic diaphragm and permitting axial but not torsional movement of the diaphragm relative to a fixed support frame to which the suspension is attached.
Prior suspensions, sometimes referred to as compliances or surrounds, have been used for supporting acoustic diaphragms, exemplified by the constructions shown in U.S. Pat. No. 1,829,355 to Houghton and U.S. Pat. No. 3,563,337 to Kawamura, and by FIGS. 10 and 11 of the drawings presented herewith as examples of other forms of suspensions. The principal objectives of such constructions, as well as of the present invention, are to prevent torsional or radial movement of the diaphragm while permitting axial movement thereof, and to minimize stress of the material of which the suspension is made, whereby to provide for long life of the suspension and to avoid distortion by permitting the diaphragm to move as nearly as possible in accurate response to the signal in the voice coil.
The two patents exemplify the state of the art as to folded surrounds and have as their principal objective the control of the low frequency end of the given transducer's frequency response. They further seek to solve the problems of achieving a large excursion without over-stressing the material or otherwise distorting its shape so as to minimize distortion of the acoustic output, to prolong the operating life, and to improve the frequency response particularly at this low, high excursion, end of their desired range.
The present invention, on the other hand, without substantially altering the behavior at the low frequency end of the transducer's range, is concerned with the first anti-nodal and second nodal resonances which together with the moving mass mark the high frequency end of this range. This invention makes possible for the first time the independent control of the high and low ends of the range.